TECHNICAL FIELD
[0001] The present disclosure relates to a gas supply device including a filter unit and
an air pump in a gas passage through which air is supplied to a target space, an interior
air adjustment device that supplies, to the target space, mixed gas generated by the
gas supply device and having a high nitrogen concentration and a low oxygen concentration,
and a container refrigeration device including the interior air adjustment device.
BACKGROUND ART
[0002] Conventionally, a container refrigeration device including a refrigerant circuit
that performs a refrigeration cycle has been used in order to cool air inside a container
used for maritime transport or the like (see, for example, Patent Literature 1). For
example, plants such as bananas and avocados are loaded in the container. Even after
being harvested, plants breathe by taking in oxygen in the air and releasing carbon
dioxide. When the plants breathe, the nutrients and moisture stored in the plants
are reduced, making the plants less fresh. Therefore, the interior of the container
preferably has a reasonably low oxygen concentration at which a respiratory problem
does not arise.
[0003] For that purpose, Patent Literature 1 discloses the following interior air adjustment
device. This interior air adjustment device uses an adsorbent that adsorbs, when pressurized,
nitrogen components in the air in order to generate nitrogen-enriched air (mixed gas)
having a higher nitrogen concentration and a lower oxygen concentration than air.
The interior air adjustment device then supplies the nitrogen-enriched air to the
interior of a container to thereby lower the oxygen concentration of the interior
space and reduce the respiration rate of plants, making it easy to keep the plants
fresh. The interior air adjustment device generates the nitrogen-enriched air through
an adsorption operation and a subsequent desorption operation. In the adsorption operation,
pressurized air is sent by an air pump into an adsorption cylinder containing an adsorbent,
and the adsorbent adsorbs nitrogen components. In the desorption operation, the air
pump sucks air from the adsorption cylinder to desorb the nitrogen components adsorbed
on the adsorbent.
[0004] Components of the interior air adjustment device are stored in a unit case having
a sealed structure. The interior air adjustment device configured as one unit is attached
in a space outside a container refrigeration device. A filter unit provided in an
air intake port is installed separately from the interior air adjustment device and
connected to the interior air adjustment device by an air hose. The filter unit is
provided with a filter, and the filter is covered with a sheet metal cover to avoid
direct contact with water.
CITATION LIST
PATENT LITERATURE
SUMMARY OF THE INVENTION
<Technical Problem>
[0006] Note that sea salt particles adhere to a filter of a device, such as the above interior
air adjustment device, used under conditions where the device may suffer from salt
damage. When the humidity becomes high, therefore, a water film is formed on the filter
due to a deliquescence phenomenon. As a result, the ventilation resistance or pressure
loss of the filter may increase, making it difficult for air to pass through the filter
during operation. However, this conventional technology cannot prevent the increase
in pressure loss and the difficulty of air passing through the filter during operation.
[0007] This problem may arise not only in the interior air adjustment device of a container
refrigeration device installed in a marine container, but also in a gas supply device
having components such as pumps and valves, which need to be resistant to salt damage,
in order to send gas such as air through a filter into, for example, a warehouse constructed
in a coastal area.
[0008] An object of the present disclosure is to prevent a phenomenon in which it becomes
difficult for air to pass through a filter of a gas supply device due to an increase
in pressure loss of the filter caused by deliquescence.
<Solution to Problem>
[0009] A first aspect of the present disclosure is based on a gas supply device including
a gas passage (40) through which gas is supplied to a target space, a filter unit
(75) provided at an inlet of the gas passage (40), and an air pump (31) provided on
the gas passage (40).
[0010] This gas supply device includes a heating unit (93) that heats gas flowing into a
filter (76) provided in the filter unit (75).
[0011] In the first aspect, the occurrence of a deliquescence phenomenon is suppressed by
heating of the filter (76), making it possible to prevent the difficulty of gas passing
through the filter (76) during operation.
[0012] A second aspect is an aspect according to the first aspect, further including a salt
amount detection unit (91) that detects an amount of salt adhering to the filter (76)
provided in the filter unit (75), and a humidity detection unit (92) that detects
a relative humidity of gas flowing into the gas passage (40) from the inlet.
[0013] A third aspect is an aspect according to the second aspect, wherein the heating unit
(93) is configured to heat the gas flowing into the filter (76) in a case where the
amount of salt detected by the salt amount detection unit (91) is equal to or higher
than a reference salt amount and the relative humidity of the gas detected by the
humidity detection unit (92) is equal to or higher than a humidity reference value.
[0014] In the second and third aspects, the gas flowing into the filter (76) is heated by
the heating unit (93) in the case where the amount of salt detected by the salt amount
detection unit (91) is equal to or higher than the reference salt amount and the relative
humidity of the gas detected by the humidity detection unit (92) is equal to or higher
than the humidity reference value. Therefore, even under a condition where the humidity
is high and deliquescence is likely to occur, the occurrence of the deliquescence
phenomenon is suppressed, making it possible to prevent the difficulty of gas passing
through the filter (76) during operation.
[0015] For example, the reference salt amount and the humidity reference value may be set
to such values that the deliquescence phenomenon immediately occurs upon detection
of these values, or may be set to a slightly low value, that is, a value at which
the deliquescence phenomenon occurs due to an increase in humidity and the pressure
loss is predicted to increase. If lower values are set, the gas flowing into the filter
(76) is heated in advance before the deliquescence phenomenon occurs.
[0016] A fourth aspect is based on an interior air adjustment device including a gas supply
device (30), and a mixed gas generator (38) that generates, from air taken in through
a filter unit (75) of the gas supply device (30), mixed gas having a higher nitrogen
concentration and a lower oxygen concentration than the air.
[0017] In this interior air adjustment device, the gas supply device (30) is the gas supply
device (30) according to any one of the first to third aspects, and the interior air
adjustment device is configured to supply the gas generated by the mixed gas generator
(38) to the target space using the air pump (31).
[0018] In the interior air adjustment device of the fourth aspect, even under the condition
where the humidity is high and deliquescence is likely to occur, the occurrence of
the deliquescence phenomenon is suppressed, making it possible to prevent the difficulty
of air passing through the filter (76) during operation.
[0019] A fifth aspect is based on a container refrigeration device including a casing (12)
mounted on a container (11), a component, of a refrigerant circuit (20), attached
to the casing (12), and an interior air adjustment device (60) attached to the casing
(12), the container refrigeration device being configured to cool an interior space
of the container (11) and to supply mixed gas to the interior space of the container
(11) by the interior air adjustment device.
[0020] In this container refrigeration device, the interior air adjustment device (60) is
the interior air adjustment device (60) according to the fourth aspect.
[0021] In the container refrigeration device of the fifth aspect, even under the condition
where the humidity is high and deliquescence is likely to occur, the occurrence of
the deliquescence phenomenon is suppressed, making it possible to prevent the difficulty
of air passing through the filter (76) during operation.
[0022] A sixth aspect is an aspect according to the fifth aspect, wherein the heating unit
(93) is configured to heat the gas using air that has passed through a condenser (22)
provided in the refrigerant circuit (20).
[0023] In the sixth aspect, even under the condition where the humidity is high and deliquescence
is likely to occur since the gas flowing into the filter (76) is heated by the air
that has passed through the condenser (22), the occurrence of the deliquescence phenomenon
is suppressed. It is possible to prevent the difficulty of gas passing through the
filter (76) during operation
<Advantageous Effects of Invention>
[0024] According to the first aspect, since the gas flowing into the filter (76) is heated
by the heating unit (93), moisture is released from the filter (76) and the occurrence
of the deliquescence phenomenon is suppressed. Therefore, according to the first aspect,
it is possible to prevent the difficulty of air passing through the filter (76) during
operation.
[0025] According to the second and third aspects, the gas flowing into the filter (76) is
heated by the heating unit (93) in the case where the amount of salt detected by the
salt amount detection unit (91) is equal to or higher than the reference salt amount
and the relative humidity of the gas detected by the humidity detection unit (92)
is equal to or higher than the humidity reference value. Therefore, under the condition
where the humidity is high and deliquescence is likely to occur, moisture is released
from the filter (76), and the occurrence of the deliquescence phenomenon is suppressed.
That is, according to the second and third aspects, it is possible to prevent the
difficulty of air passing through the filter (76) during operation. If the reference
salt amount and the humidity reference value are set low, the gas can be heated when
the deliquescence phenomenon is predicted to occur with an increase in humidity, making
it possible to prevent an increase in pressure loss.
[0026] According to the fourth aspect, in the interior air adjustment device (60), it is
possible to prevent the difficulty of air passing through the filter (76) during operation.
[0027] According to the fifth aspect, in the container refrigeration device, it is possible
to prevent the difficulty of air passing through the filter (76) during operation.
[0028] According to the sixth aspect, the gas flowing into the filter (76) is heated by
the condenser (22) of the refrigerant circuit (20), making it possible to prevent,
with a simple configuration, the difficulty of the gas passing through the filter
(76) during operation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029]
FIG. 1 is a perspective view of a container refrigeration device according to an embodiment
as viewed from the outside.
FIG. 2 is a side sectional view illustrating a schematic configuration of the container
refrigeration device.
FIG. 3 is a piping system diagram illustrating a configuration of a refrigerant circuit
of the container refrigeration device.
FIG. 4 is a piping system diagram illustrating a configuration of a CA device of the
container refrigeration device and an air flow during a first operation.
FIG. 5 is a piping system diagram illustrating the configuration of the CA device
of the container refrigeration device and an air flow during a second operation.
FIG. 6 is an enlarged perspective view of a main part of the container refrigeration
device.
FIG. 7 is a graph illustrating, based on past data, the relationship between the amount
of salt on a filter surface and the rate of increase in pressure loss when a deliquescence
phenomenon occurs at the corresponding amount of salt.
FIG. 8 is a graph illustrating, based on past data, the relationship between pump
operation time and the amount of salt on the filter surface.
DESCRIPTION OF EMBODIMENTS
[0030] An embodiment will be described in detail below with reference to the drawings. The
present embodiment relates to a container refrigeration device provided with an interior
air adjustment device including a gas supply device of the present disclosure. Note
that the following description of the preferred embodiment is merely illustrative
in nature and is not intended to limit the present disclosure, applications of the
disclosure, or use of the disclosure.
[0031] As illustrated in FIGS. 1 and 2, a container refrigeration device (10) is provided
in a container (11) used for maritime transport and the like, and cools interior air
of the container (11). Plants (15) are stored in boxes in an interior space (target
space) (S) of the container (11). The plants (15) breathe by taking in oxygen (O
2) in the air and releasing carbon dioxide (CO
2). Examples of the plants include fruits such as bananas and avocados, vegetables,
grains, bulbs, and fresh flowers.
[0032] The container (11) is formed in an elongated box shape with one end face opened.
The container refrigeration device (10) includes a casing (12), a refrigerant circuit
(20), and a CA device (interior air adjustment device/controlled atmosphere system)
(60), and is attached to the container (11) so as to close the open end of the container
(11).
<Casing>
[0033] As illustrated in FIG. 2, the casing (12) includes an outer wall (12a) located on
the outer side of the container (11), and an inner wall (12b) located on the inner
side of the container (11). The outer wall (12a) and the inner wall (12b) are made
of, for example, an aluminum alloy.
[0034] The outer wall (12a) is attached to a peripheral edge of the opening of the container
(11) so as to close the open end of the container (11). The outer wall (12a) is formed
with a lower part thereof bulging toward the interior of the container (11).
[0035] The inner wall (12b) is disposed while facing the outer wall (12a). The inner wall
(12b) bulges toward the interior in a manner corresponding to the lower part of the
outer wall (12a). A heat insulating material (12c) is provided in a space between
the inner wall (12b) and the outer wall (12a).
[0036] As described above, the lower part of the casing (12) is formed while bulging toward
the interior of the container (11). As a result, an outer storage space (S1) is formed
outside the container (11) at the lower part of the casing (12), and an inner storage
space (S2) is formed inside the container (11) at an upper part of the casing (12).
[0037] As illustrated in FIG. 1, two service openings (14) for maintenance are formed in
the casing (12) side by side in the width direction. The two service openings (14)
are closed by first and second service doors (16A, 16B) that can be opened and closed.
Like the casing (12), the first and second service doors (16A, 16B) each include an
outer wall, an inner wall, and a heat insulating material.
[0038] As illustrated in FIG. 2, a partition plate (18) is disposed inside the container
(11). The partition plate (18) is configured as a substantially rectangular plate
member, and is erected while facing a surface of the casing (12) on the inner side
of the container (11). The partition plate (18) separates the interior space (S) and
the inner storage space (S2) of the container (11).
[0039] A suction port (18a) is formed between an upper end of the partition plate (18) and
a ceiling surface in the container (11). The interior air of the container (11) is
taken into the inner storage space (S2) through the suction port (18a).
[0040] A section wall (13) extending in the horizontal direction is provided in the inner
storage space (S2). The section wall (13) is attached to an upper end portion of the
partition plate (18). An opening, in which an inner fan (26) to be described later
is installed, is formed in the section wall (13). The section wall (13) separates
the inner storage space (S2) into a primary space (S21) on the suction side of the
inner fan (26) and a secondary space (S22) on the blow-out side of the inner fan (26).
In the present embodiment, the inner storage space (S2) is separated vertically by
the section wall (13) into the upper primary space (S21) on the suction side and the
lower secondary space (S22) on the blow-out side.
[0041] A floor plate (19) is provided in the container (11) with a gap between a bottom
surface of the container (11) and the floor plate (19). The boxed plants (15) are
placed on the floor plate (19). An underfloor channel (19a) is formed between the
bottom surface in the container (11) and the floor plate (19). A gap communicating
with the underfloor channel (19a) is provided between a lower end of the partition
plate (18) and the bottom surface in the container (11).
[0042] A blow-out port (18b) is formed in the floor plate (19) at the back side (right side
in FIG. 2) of the container (11). Air that has been cooled by the container refrigeration
device (10) is blown into the interior space (S) of the container (11) through the
blow-out port (18b).
<Configuration and arrangement of refrigerant circuit and the like>
[0043] As illustrated in FIG. 3, the refrigerant circuit (20) is a closed circuit configured
by connecting a compressor (21), a condenser (22), an expansion valve (23), and an
evaporator (24) in that order by a refrigerant pipe (20a).
[0044] An outer fan (25) is provided near the condenser (22). The outer fan (25) is driven
to rotate by an outer fan motor (25a), and guides the air outside the container (11)
(outdoor air) into the outer storage space (S1) and to the condenser (22). In the
condenser (22), heat is exchanged between refrigerant pressurized by the compressor
(21) and flowing through the condenser (22) and the outdoor air guided to the condenser
(22) by the outer fan (25). In the present embodiment, the outer fan (25) includes
a propeller fan.
[0045] Two inner fans (26) are provided near the evaporator (24). The inner fans (26) are
driven to rotate by an inner fan motor (26a), and guide the interior air of the container
(11) from the suction port (18a) and blow the air onto the evaporator (24). In the
evaporator (24), heat is exchanged between the refrigerant decompressed by the expansion
valve (23) and flowing through the evaporator (24) and the interior air guided to
the evaporator (24) by the inner fan (26).
[0046] As illustrated in FIG. 2, the inner fan (26) includes a propeller fan (rotary blade)
(27a), a plurality of stationary blades (27b), and a fan housing (27c). The propeller
fan (27a) is coupled to the inner fan motor (26a), is driven to rotate around the
rotation axis by the inner fan motor (26a), and blows air in the axial direction.
The plurality of stationary blades (27b) is provided on the blow-out side of the propeller
fan (27a) and straightens the flow of air swirling after being blown from the propeller
fan (27a). The fan housing (27c) includes a cylindrical member having an inner peripheral
surface to which the plurality of stationary blades (27b) is attached. The fan housing
(27c) extends to and surrounds the outer periphery of the propeller fan (27a).
[0047] As illustrated in FIG. 1, the compressor (21) and the condenser (22) are stored in
the outer storage space (S1). The condenser (22) is provided at a vertically central
portion of the outer storage space (S1) while separating the outer storage space (S1)
into a lower first space (S11) and an upper second space (S12). The compressor (21),
an inverter box (29) in which a drive circuit for driving the compressor (21) at a
variable speed is stored, and a gas supply device (30) of the CA device (60) are provided
in the first space (S11). Meanwhile, the outer fan (25) and an electric component
box (17) are provided in the second space (S12). The first space (S11) is open to
the space outside the container (11), while the second space (S12) is partially closed
off from the outside space by a plate-shaped member such that only the blow-out port
of the outer fan (25) opens to the outside space.
[0048] Meanwhile, as illustrated in FIG. 2, the evaporator (24) is stored in the secondary
space (S22) of the inner storage space (S2). The two inner fans (26) are provided
above the evaporator (24) in the inner storage space (S2), side by side in the width
direction of the casing (12).
<CA device>
[0049] As illustrated in FIG. 4, the CA device (60) includes the gas supply device (30),
an exhaust unit (46), a sensor unit (50), a control unit (55), and a filter unit (75).
The CA device (60) adjusts the oxygen concentration and the carbon dioxide concentration
of the interior air of the container (11). Note that each "concentration" used in
the following description refers to "volume concentration". The control unit (55)
includes a microcomputer and a memory device (specifically, a semiconductor memory)
that stores software for operating the microcomputer. The control unit (55) controls
each component of the CA device (60).
[Gas supply device]
-Configuration of gas supply device-
[0050] The gas supply device (30) sucks air (gas) from the filter unit (75) and supplies
nitrogen-enriched air to the interior space (S), i.e., the target space (S), of the
container (11). In the present embodiment, the gas supply device (30) adopts the vacuum
pressure swing adsorption (VPSA) technology. As illustrated in FIG. 1, the gas supply
device (30) is disposed at a lower left corner of the outer storage space (S1).
[0051] As illustrated in FIG. 4, the gas supply device (30) includes an air circuit (3)
and a unit case (36) in which the components of the air circuit (3) are stored. An
air pump (31), a first direction control valve (32), a second direction control valve
(33), a first adsorption cylinder (34), and a second adsorption cylinder (35) are
connected to the air circuit (3). An adsorbent for adsorbing nitrogen components in
the air is provided in each of the first adsorption cylinder (34) and the second adsorption
cylinder (35). As described above, the gas supply device (30) is configured as one
unit with the components thereof stored inside the unit case (36), and configured
to be attached additionally to the container refrigeration device (10).
(Air pump)
[0052] The air pump (31) is provided on a gas passage (40) including an outdoor air passage
(41), a discharge passage (42), a suction passage (43), and a supply passage (44).
The filter unit (75) to be described later is provided at an inlet of the gas passage
(40).
[0053] The air pump (31) is provided inside the unit case (36) and includes a first pump
mechanism (pressurizing unit) (31a) and a second pump mechanism (decompressing unit)
(31b) that each suck, pressurize and discharge air. The first pump mechanism (31a)
and the second pump mechanism (31b) are connected to a drive shaft of a motor (31c),
and driven to rotate by the motor (31c), thereby sucking, pressurizing and discharging
air.
[0054] One end of the outdoor air passage (41), which penetrates the unit case (36) in and
out, is connected to a suction port of the first pump mechanism (31a). The filter
unit (75) including an air filter is provided at the other end of the outdoor air
passage (41). The outdoor air passage (41) includes a flexible tube. Although not
illustrated, the other end of the outdoor air passage (41) provided with the filter
unit (75) is provided in the second space (S12) above the condenser (22) in the outer
storage space (S1). This configuration allows the first pump mechanism (31a) to suck
and pressurize outdoor air from which moisture has been removed when the air has flowed
into the unit case (36) from the outside through the filter unit (75) provided at
the other end of the outdoor air passage (41). Meanwhile, one end of the discharge
passage (42) is connected to a discharge port of the first pump mechanism (31a). The
other end of the discharge passage (42) branches into two passages on the downstream
side and is connected to each of the first direction control valve (32) and the second
direction control valve (33).
[0055] One end of the suction passage (43) is connected to a suction port of the second
pump mechanism (31b). The other end of the suction passage (43) branches into two
passages on the upstream side and is connected to each of the first direction control
valve (32) and the second direction control valve (33). Meanwhile, one end of the
supply passage (44) is connected to a discharge port of the second pump mechanism
(31b). The other end of the supply passage (44) opens in the secondary space (S22)
on the blow-out side of the inner fan (26) in the inner storage space (S2) of the
container (11). The other end of the supply passage (44) is provided with a check
valve (65) that allows air to flow unidirectionally from the one end to the other
end of the supply passage (44) and prevents backflow of the air.
[0056] In the present embodiment, the discharge passage (42) and the suction passage (43)
are connected to each other by a bypass passage (47). The bypass passage (47) is provided
with a bypass on-off valve (48) that is opened and closed under the control of the
control unit (55).
[0057] The first pump mechanism (31a) and the second pump mechanism (31b) of the air pump
(31) each include an oilless pump that does not use lubricating oil. Two fans (49)
for cooling the air pump (31) by blowing air toward the air pump (31) are provided
near one side of the air pump (31).
(Mixed gas generator)
[0058] In the present embodiment, the following direction control valves (32, 33) and adsorption
cylinders (34, 35) constitute a mixed gas generator (38).
(Direction control valve)
[0059] The first direction control valve (32) and the second direction control valve (33)
are provided between the air pump (31) and the first and second adsorption cylinders
(34, 35) in the air circuit (3). The first direction control valve (32) and the second
direction control valve (33) switch the connection state between the air pump (31)
and the first and second adsorption cylinders (34, 35) among three (i.e., first to
third) connection states to be described later. This switching operation is controlled
by the control unit (55).
[0060] Specifically, the first direction control valve (32) is connected to: the discharge
passage (42) connected to the discharge port of the first pump mechanism (31a); the
suction passage (43) connected to the suction port of the second pump mechanism (31b);
and one end (inlet during pressurization) of the first adsorption cylinder (34). The
first direction control valve (32) is switched between a first state (illustrated
in FIG. 4) and a second state (illustrated in FIG. 5). In the first state, the first
adsorption cylinder (34) communicates with the discharge port of the first pump mechanism
(31a) but is closed off from the suction port of the second pump mechanism (31b).
In the second state, the first adsorption cylinder (34) communicates with the suction
port of the second pump mechanism (31b) but is closed off from the discharge port
of the first pump mechanism (31a).
[0061] The second direction control valve (33) is connected to: the discharge passage (42)
connected to the discharge port of the first pump mechanism (31a); the suction passage
(43) connected to the suction port of the second pump mechanism (31b); and one end
of the second adsorption cylinder (35). The second direction control valve (33) is
switched between a first state (illustrated in FIG. 4) and a second state (illustrated
in FIG. 5). In the first state, the second adsorption cylinder (35) communicates with
the suction port of the second pump mechanism (31b) but is closed off from the discharge
port of the first pump mechanism (31a). In the second state, the second adsorption
cylinder (35) communicates with the discharge port of the first pump mechanism (31a)
but is closed off from the suction port of the second pump mechanism (31b).
[0062] When the first direction control valve (32) and the second direction control valve
(33) are both set to the first state, the air circuit (3) is switched to the first
connection state (see FIG. 4) in which the discharge port of the first pump mechanism
(31a) and the first adsorption cylinder (34) are connected and the suction port of
the second pump mechanism (31b) and the second adsorption cylinder (35) are connected.
In this state, the adsorption operation of adsorbing nitrogen components in the outdoor
air on the adsorbent is performed in the first adsorption cylinder (34), while the
desorption operation of desorbing the nitrogen components adsorbed on the adsorbent
is performed in the second adsorption cylinder (35).
[0063] When the first direction control valve (32) and the second direction control valve
(33) are both set to the second state, the air circuit (3) is switched to the second
connection state (see FIG. 5) in which the discharge port of the first pump mechanism
(31a) and the second adsorption cylinder (35) are connected and the suction port of
the second pump mechanism (31b) and the first adsorption cylinder (34) are connected.
In this state, the adsorption operation is performed in the second adsorption cylinder
(35) while the desorption operation is performed in the first adsorption cylinder
(34).
[0064] When the first direction control valve (32) is set to the first state and the second
direction control valve (33) is set to the second state, the air circuit (3) is switched
to the third connection state (not illustrated) in which the discharge port of the
first pump mechanism (31a) is connected to each of the first adsorption cylinder (34)
and the second adsorption cylinder (35). In this state, the first adsorption cylinder
(34) and the second adsorption cylinder (35) are both connected to the discharge port
of the first pump mechanism (31a), and the first pump mechanism (31a) supplies pressurized
outdoor air to each of the first adsorption cylinder (34) and the second adsorption
cylinder (35). In this state, the adsorption operation is performed in each of the
first adsorption cylinder (34) and the second adsorption cylinder (35).
(Adsorption cylinder)
[0065] The first adsorption cylinder (34) and the second adsorption cylinder (35) each include
a cylindrical member filled with an adsorbent. The adsorbent filling each of the first
adsorption cylinder (34) and the second adsorption cylinder (35) has a property of
adsorbing nitrogen components when pressurized and desorbing the adsorbed nitrogen
components when decompressed.
[0066] The adsorbent filling each of the first adsorption cylinder (34) and the second adsorption
cylinder (35) includes, for example, porous zeolite having pores with a pore diameter
smaller than the molecular diameter of nitrogen molecules (3.0 angstroms) but larger
than the molecular diameter of oxygen molecules (2.8 angstroms). The adsorbent including
zeolite having such a pore diameter can adsorb nitrogen components in the air.
[0067] Since an electric field is present and polarity is generated in the pores of the
zeolite due to the presence of cations, the zeolite has a property of adsorbing polar
molecules such as water molecules. Therefore, not only nitrogen in the air but also
moisture (water vapor) in the air is adsorbed on the adsorbent including zeolite and
filling each of the first adsorption cylinder (34) and the second adsorption cylinder
(35). The moisture adsorbed on the adsorbent is desorbed from the adsorbent together
with the nitrogen components in the desorption operation. As a result, nitrogen-enriched
air containing the moisture is supplied to the interior space (S) of the container
(11), making it possible to increase the humidity of the interior space (S). Furthermore,
since the adsorbent is regenerated, the service life of the adsorbent can be extended.
[0068] With this configuration, when pressurized outdoor air is supplied from the air pump
(31) and the inside of the first adsorption cylinder (34) and the second adsorption
cylinder (35) is pressurized, nitrogen components in the outdoor air are adsorbed
on the adsorbents. As a result, the nitrogen components are reduced as compared to
the outdoor air, whereby oxygen-enriched air having a lower nitrogen concentration
and a higher oxygen concentration than the outdoor air is generated. When the air
inside the first adsorption cylinder (34) and the second adsorption cylinder (35)
is sucked and the inside of the cylinders is decompressed by the air pump (31), on
the other hand, the nitrogen components adsorbed on the adsorbents are desorbed. As
a result, the nitrogen components are increased as compared to the outdoor air, whereby
nitrogen-enriched air having a higher nitrogen concentration and a lower oxygen concentration
than the outdoor air is generated. In the present embodiment, nitrogen-enriched air
having a component ratio of, for example, 92% nitrogen concentration and 8% oxygen
concentration is generated.
[0069] One end of an oxygen discharge passage (45) is connected to the other end (outlet
during pressurization) of each of the first adsorption cylinder (34) and the second
adsorption cylinder (35). The oxygen-enriched air generated in the first adsorption
cylinder (34) and the second adsorption cylinder (35) from the outdoor air pressurized
and supplied by the first pump mechanism (31a) is guided to the outside of the container
(11) through the oxygen discharge passage (45). The one end of the oxygen discharge
passage (45) branches into two passages and is connected to the other end of each
of the first adsorption cylinder (34) and the second adsorption cylinder (35). The
other end of the oxygen discharge passage (45) is open to the outside of the gas supply
device (30), that is, outside the container (11). A check valve (61) is provided in
each of a portion of the oxygen discharge passage (45) connected to the other end
of the first adsorption cylinder (34) and a portion of the oxygen discharge passage
(45) connected to the other end of the second adsorption cylinder (35). The check
valve (61) prevents backflow of air from the oxygen discharge passage (45) to the
first adsorption cylinder (34) or the second adsorption cylinder (35).
[0070] A check valve (62) and an orifice (63) are provided in that order from the one end
to the other end in a middle part of the oxygen discharge passage (45). The check
valve (62) prevents backflow of nitrogen-enriched air from an exhaust connection passage
(71), which will be described later, to the first adsorption cylinder (34) and the
second adsorption cylinder (35). The orifice (63) decompresses the oxygen-enriched
air that has flowed out of the first adsorption cylinder (34) and the second adsorption
cylinder (35) before the air is discharged to the outside.
(Supply and discharge switching mechanism)
[0071] The air circuit (3) is provided with a supply and discharge switching mechanism (70).
The supply and discharge switching mechanism (70) switches the operation between a
gas supply operation to be described later (see FIGS. 4 and 5) of supplying generated
nitrogen-enriched air to the interior space (S) of the container (11) and a gas discharge
operation (not illustrated) of discharging the generated nitrogen-enriched air to
the outside of the container (11). The supply and discharge switching mechanism (70)
includes the exhaust connection passage (71), an exhaust on-off valve (72), and a
supply-side on-off valve (73).
[0072] The exhaust connection passage (71) has one end connected to the supply passage (44)
and the other end connected to the oxygen discharge passage (45). The other end of
the exhaust connection passage (71) is connected to a portion that is closer to the
outside of the container than the orifice (63) of the oxygen discharge passage (45).
[0073] The exhaust on-off valve (72) is provided in the exhaust connection passage (71).
The exhaust on-off valve (72) is provided in a middle part of the exhaust connection
passage (71) and includes an electromagnetic valve. The electromagnetic valve is switched
between an open state in which the nitrogen-enriched air flowing from the supply passage
(44) is allowed to pass, and a close state in which the flow of the nitrogen-enriched
air is blocked. The exhaust on-off valve (72) is opened and closed under the control
of the control unit (55).
[0074] The supply-side on-off valve (73) is provided closer to the other end side of the
supply passage (44) (closer to the interior of the container) than a portion of the
supply passage (44) to which the exhaust connection passage (71) is connected. The
supply-side on-off valve (73) includes an electromagnetic valve and is provided in
the supply passage (44) at a portion closer to the interior of the container than
the portion to which the exhaust connection passage (71) is connected. The electromagnetic
valve is switched between an open state in which the nitrogen-enriched air is allowed
to pass toward the interior of the container, and a close state in which the flow
of the nitrogen-enriched air toward the interior of the container is blocked. The
supply-side on-off valve (73) is opened and closed under the control of the control
unit (55).
(Measurement unit)
[0075] The air circuit (3) is provided with a measurement unit (80). The measurement unit
(80) performs a supplied air measurement operation (not illustrated) of measuring
the concentration of the generated nitrogen-enriched air using an oxygen sensor (51)
of the sensor unit (50) to be described later that is provided in the interior space
(S) of the container (11). The measurement unit (80) includes a branch pipe (measurement
passage) (81) and a measurement on-off valve (82), and is configured to branch part
of the nitrogen-enriched air flowing through the supply passage (44) and guide the
air to the oxygen sensor (51).
[0076] Specifically, the branch pipe (81) has one end connected to the supply passage (44)
and the other end coupled to an oxygen sensor box (51a), to be described later, of
the oxygen sensor (51). In the present embodiment, the branch pipe (81) branches from
the supply passage (44) inside the unit case (36) and extends to the outside of the
unit case.
[0077] The measurement on-off valve (82) is provided in the branch pipe (81) inside the
unit case. The measurement on-off valve (82) includes an electromagnetic valve. The
electromagnetic valve is switched between an open state in which the nitrogen-enriched
air is allowed to pass through the branch pipe (81), and a close state in which the
flow of the nitrogen-enriched air through the branch pipe (81) is blocked. The measurement
on-off valve (82) is opened and closed under the control of the control unit (55).
The measurement on-off valve (82) is opened only when the supplied air measurement
operation to be described later is performed, and closed in other modes, although
the details thereof will be described later.
[Exhaust unit]
-Configuration of exhaust unit-
[0078] As illustrated in FIG. 2, the exhaust unit (46) includes an exhaust passage (46a)
that connects the inner storage space (S2) and the space outside the container, an
exhaust valve (46b) connected to the exhaust passage (46a), and a membrane filter
(46c) provided at an inflow end (end inside the container) of the exhaust passage
(46a). The exhaust passage (46a) penetrates the casing (12) in and out. The exhaust
valve (46b) is provided in the exhaust passage (46a) inside the container and includes
an electromagnetic valve. The electromagnetic valve is switched between an open state
in which air is allowed to pass through the exhaust passage (46a), and a close state
in which the flow of the air through the exhaust passage (46a) is blocked. The exhaust
valve (46b) is opened and closed under the control of the control unit (55).
-Operation of exhaust unit-
[0079] When the control unit (55) opens the exhaust valve (46b) during rotation of the inner
fan (26), an exhaust operation is performed in which the air (interior air) in the
inner storage space (S2) connected to the interior space (S) is discharged to the
outside of the container.
[0080] Specifically, when the inner fan (26) rotates, the pressure in the secondary space
(S22) on the blow-out side becomes higher than the pressure in the space outside the
container (atmospheric pressure). Therefore, when the exhaust valve (46b) is open,
the pressure difference generated between both ends of the exhaust passage (46a) (pressure
difference between the space outside the container and the secondary space (S22))
causes the air in the inner storage space (S2) connected to the interior space (S)
(interior air) to be discharged to the space outside the container through the exhaust
passage (46a).
[Sensor unit]
-Configuration of sensor unit-
[0081] As illustrated in FIG. 2, the sensor unit (50) is provided in the secondary space
(S22) on the blow-out side of the inner fan (26) in the inner storage space (S2).
The sensor unit (50) includes an oxygen sensor (51), a carbon dioxide sensor (52),
a fixed plate (53), a membrane filter (54), a connecting pipe (56), and an exhaust
pipe (57).
[0082] The oxygen sensor (51) includes the oxygen sensor box (51a) in which a galvanic cell
type sensor is accommodated. The oxygen sensor (51) measures the oxygen concentration
in the gas in the oxygen sensor box (51a) by measuring the value of current flowing
through electrolyte of the galvanic cell type sensor. An outer surface of the oxygen
sensor box (51a) is fixed to the fixed plate (53). An opening is formed in an outer
surface of the oxygen sensor box (51a) opposite to the surface fixed to the fixed
plate (53), and the membrane filter (54) having air permeability and waterproofness
is attached in the opening. One end of the connecting pipe (56) is coupled to one
side surface of the oxygen sensor box (51a) via a connector. Furthermore, the branch
pipe (81) of the measurement unit (80) is coupled to the lower surface of the oxygen
sensor box (51a) via a connector (pipe joint).
[0083] The carbon dioxide sensor (52) includes a carbon dioxide sensor box (52a). The carbon
dioxide sensor (52) is a non dispersive infrared (NDIR) sensor that measures the carbon
dioxide concentration in the gas by emitting infrared rays to the gas in the carbon
dioxide sensor box (52a) and measuring the absorption amount of infrared rays having
a wavelength specific to carbon dioxide. The other end of the connecting pipe (56)
is coupled to one side surface of the carbon dioxide sensor box (52a) via a connector.
One end of the exhaust pipe (57) is coupled to the other side surface of the carbon
dioxide sensor box (52a) via a connector.
[0084] The fixed plate (53) is fixed to the casing (12) with the oxygen sensor (51) and
the carbon dioxide sensor (52) attached to the fixed plate (53).
[0085] As described above, the connecting pipe (56) is coupled to the side surface of the
oxygen sensor box (51a) and the side surface of the carbon dioxide sensor box (52a),
and allows the internal space of the oxygen sensor box (51a) to communicate with the
internal space of the carbon dioxide sensor box (52a).
[0086] As described above, the exhaust pipe (57) has one end coupled to the other side surface
of the carbon dioxide sensor box (52a) and the other end opened near the suction port
of the inner fan (26). That is, the exhaust pipe (57) allows the internal space of
the carbon dioxide sensor box (52a) to communicate with the primary space (S21) of
the inner storage space (S2).
-Concentration measurement operation-
[0087] The secondary space (S22) and the primary space (S21) of the inner storage space
(S2) communicate with each other through an air passage (58) formed by the membrane
filter (54), the internal space of the oxygen sensor box (51a), the connecting pipe
(56), the internal space of the carbon dioxide sensor box (52a), and the exhaust pipe
(57). During operation of the inner fan (26), therefore, the pressure in the primary
space (S21) is lower than the pressure in the secondary space (S22). This pressure
difference allows the interior air to flow from the secondary space (S22) toward the
primary space (S21) through the air passage (58) to which the oxygen sensor (51) and
the carbon dioxide sensor (52) are connected. In this way, the interior air passes
through the oxygen sensor (51) and the carbon dioxide sensor (52) in that order; in
the meantime, the oxygen sensor (51) measures the oxygen concentration of the interior
air and the carbon dioxide sensor (52) measures the carbon dioxide concentration of
the interior air.
[Control unit]
[0088] The control unit (55) is configured to execute a concentration adjustment operation
of setting the oxygen concentration and the carbon dioxide concentration of the interior
air of the container (11) to desired concentrations. Specifically, the control unit
(55) controls, based on the measurement results of the oxygen sensor (51) and the
carbon dioxide sensor (52), the operation of the gas supply device (30) and the exhaust
unit (46) such that the compositions (oxygen concentration and carbon dioxide concentration)
of the interior air of the container (11) become desired compositions (for example,
oxygen concentration: 3%, carbon dioxide concentration: 5%).
[Filter unit]
[0089] As illustrated in FIGS. 1 and 6, the gas supply device (30) is disposed at the lower
left corner of the outer storage space (S1) (left end below the condenser (22)), while
the filter unit (75) provided for taking air into the gas supply device (30) is disposed
on the left side of the electric component box (17) when the outer storage space (S1)
is viewed from the front. Specifically, the filter unit (75) is disposed on the left
inner surface of the casing (11) in the outer storage space (S1). One end of an air
tube (85), which constitutes the outdoor air passage (41) for sucking air, is connected
to the air pump (31) in the unit case (36), and the filter unit (75) is connected
to the other end of the air tube (85). In the filter unit, a plurality of (three or
four) surfaces of a hollow filter box other than the surface to which the air tube
is connected includes air suction ports for sucking air, and an air filter (76) is
attached to each of the air suction ports. The air filter (76) includes a membrane
filter having air permeability and waterproofness.
[Suppression of pressure loss of filter]
[0090] The gas supply device (30) of the present embodiment includes a heating unit (93)
(see FIGS. 4 and 5) that heats gas flowing into the filter (76) provided in the filter
unit (75). The gas supply device (30) also includes a salt amount detection unit (91)
(see FIG. 6) that detects the amount of salt adhering to the air filter (76), and
a humidity detection unit (92) that detects the humidity of gas flowing into the gas
passage (40) through the inlet.
[0091] The control unit (55) includes a pressure loss comparison unit (55b) and a heating
control unit (55c). The pressure loss comparison unit (55b) compares an actual pressure
loss value with the pressure loss reference value when the humidity detection value
detected by the humidity detection unit exceeds a deliquescence reference humidity.
The heating control unit (55c) causes the heating unit (93) to heat the gas flowing
into the air filter (76) in a case where the amount of salt detected by the salt amount
detection unit (91) is equal to or higher than a reference salt amount and the relative
humidity of the gas detected by the humidity detection unit (92) is equal to or higher
than a humidity reference value.
[0092] The control unit (55) also includes a pressure loss prediction unit (55a) that predicts
the pressure loss of the filter when a deliquescence phenomenon occurs, based on the
amount of salt detected by the salt amount detection unit (91) and the humidity of
the gas detected by the humidity detection unit (92). The pressure loss comparison
unit (55b) is also configured to be able to compare a predicted pressure loss value
of the pressure loss prediction unit (55a) with a predetermined pressure loss reference
value when the humidity detected by the humidity detection unit (92) is smaller than
the deliquescence reference humidity, in addition to comparing the actual pressure
loss value with the pressure loss reference value.
[0093] The heating unit (93) is configured to heat, under the control of the heating control
unit (55c), the gas flowing into the gas passage (40) using the air that has passed
through the condenser (22) provided in the refrigerant circuit (20).
[0094] If an atmospheric corrosion monitor (ACM) sensor is used as the salt amount detection
unit (91), the amount of salt can be directly measured by that sensor. The humidity
detection unit (92) is disposed near the filter unit (75) in order to measure the
humidity of the air around the air filter (76).
[0095] In the present embodiment, the gas flowing into the air filter (76) is heated when
the salt attached to the air filter (76) affects the pressure loss due to the occurrence
of the deliquescence phenomenon. It is only necessary to exercise control based on
the actual amount of salt and the actual humidity. That is, in the present embodiment,
it is not absolutely necessary to exercise control based on a predicted value using
the pressure loss prediction unit (55a). It is only necessary to exercise control
based at least on an actual value.
-Increase in pressure loss and heating of gas-
[0096] If the humidity of the outdoor air exceeds 75%, the deliquescence phenomenon usually
occurs at the air filter (76). In the present embodiment, therefore, control is exercised
for causing the heating unit (93) to heat the gas flowing into the air filter (76)
in accordance with the amount of salt in the air filter (76) and the humidity of the
outdoor air. Specifically, the heating unit (93) heats the gas flowing into the air
filter (76) in a case where the amount of salt detected by the salt amount detection
unit (91) is equal to or higher than the reference salt amount and the relative humidity
of the gas detected by the humidity detection unit (92) is equal to or higher than
the humidity reference value (75%).
[0097] The above control is an example of control exercised based on an actual value of
the pressure loss, and control based on a predicted value is exercised as follows.
First, FIG. 7 is a graph illustrating, based on past data, the relationship between
the amount of salt on a filter surface and the rate of increase in pressure loss when
a deliquescence phenomenon occurs at the corresponding amount of salt, and FIG. 8
is a graph illustrating, based on past data, the relationship between pump operation
time and the amount of salt on the filter surface. Here, as described above, the deliquescence
phenomenon generally occurs when the relative humidity reaches about 75%. The pressure
loss increases as the humidity rises.
[0098] The pressure loss prediction unit (55a) measures the suction pressure of the air
pump (31) using a pressure sensor (not illustrated) provided in the gas passage (40).
In a case where the humidity of the outdoor air at the time of the measurement is,
for example, 75% or less, the pressure loss prediction unit (55a) predicts the rate
of increase in pressure loss when the deliquescence phenomenon occurs at a high humidity
(e.g. 90%) from past data based on the graph in FIG. 7, and then predicts whether
the pressure loss exceeds a predetermined threshold (pressure loss reference value)
during operation. When the predicted pressure loss value exceeds the pressure loss
reference value, the heating control unit (55c) causes the heating unit (93) to heat
the gas (outdoor air) flowing into the air filter (76).
[0099] Here, as illustrated in FIG. 8, the amount of salt on the filter surface increases
as the operation time is extended. As illustrated in FIG. 7, as the amount of salt
on the filter surface increases, the pressure loss when the deliquescence phenomenon
occurs increases. For example, in FIG. 7, when the amount of salt exceeds 0.05 g/m
2, the pressure loss is substantially doubled (about 100% increase). In the present
embodiment, therefore, the gas (outdoor air) flowing into the air filter (76) is heated
at the suction pressure of -24.5 KPa, although the gas is usually heated when the
suction pressure reaches -49 KPa at a normal humidity. This makes it possible to avoid
in advance a phenomenon in which the pressure loss increases due to the deliquescence
that occurs at the air filter (76) at a high humidity. Note that the above value of
the suction pressure is merely an example.
-Operation-
<Operation of refrigerant circuit>
[0100] In the present embodiment, a unit controller (100) illustrated in FIG. 3 performs
a cooling operation for cooling the interior air of the container (11).
[0101] During the cooling operation, the unit controller (100) controls the operations of
the compressor (21), the expansion valve (23), the outer fan (25), and the inner fan
(26) based on the measurement result of a temperature sensor (not illustrated), such
that the temperature of the interior air reaches a desired target temperature. At
this time, refrigerant circulates and a vapor compression refrigeration cycle is performed
in the refrigerant circuit (20). Then, the interior air of the container (11) that
has been guided to the inner storage space (S2) by the inner fan (26) is cooled by
the refrigerant flowing through the evaporator (24) when the air passes through the
evaporator (24). The interior air that has been cooled in the evaporator (24) passes
through the underfloor channel (19a) and is blown out again into the interior space
(S) of the container (11) through the blow-out port (18b). As a result, the interior
air of the container (11) is cooled.
<Basic operation of gas supply device>
[0102] In the gas supply device (30), a first operation (see FIG. 4) and a second operation
(see FIG. 5) are repeated alternately at predetermined time intervals (for example,
14.5 seconds), whereby nitrogen-enriched air and oxygen-enriched air are generated.
In the first operation, the first adsorption cylinder (34) is pressurized and at the
same time the second adsorption cylinder (35) is decompressed, whereas in the second
operation, the first adsorption cylinder (34) is decompressed and at the same time
the second adsorption cylinder (35) is pressurized. In the present embodiment, a pressure
equalizing operation (not illustrated), in which both the first adsorption cylinder
(34) and the second adsorption cylinder (35) are pressurized, is performed for a predetermined
time (for example, 1.5 seconds) between the first operation and the second operation.
The operation is switched by the control unit (55) operating the first direction control
valve (32) and the second direction control valve (33).
«First operation»
[0103] In the first operation, the control unit (55) switches both the first direction control
valve (32) and the second direction control valve (33) to the first state illustrated
in FIG. 4. The air circuit (3) is thus switched to the first connection state in which
the first adsorption cylinder (34) communicates with the discharge port of the first
pump mechanism (31a) but is closed off from the suction port of the second pump mechanism
(31b), while the second adsorption cylinder (35) communicates with the suction port
of the second pump mechanism (31b) but is closed off from the discharge port of the
first pump mechanism (31a).
[0104] The first pump mechanism (31a) supplies pressurized outdoor air to the first adsorption
cylinder (34). Nitrogen components contained in the air flowing into the first adsorption
cylinder (34) are adsorbed on the adsorbent in the first adsorption cylinder (34).
As described above, during the first operation, the pressurized outdoor air is supplied
from the first pump mechanism (31a) to the first adsorption cylinder (34) and the
nitrogen components in the outdoor air are adsorbed on the adsorbent in the first
adsorption cylinder (34). As a result, oxygen-enriched air having a lower nitrogen
concentration and a higher oxygen concentration than the outdoor air is generated.
The oxygen-enriched air flows from the first adsorption cylinder (34) to the oxygen
discharge passage (45).
[0105] Meanwhile, the second pump mechanism (31b) sucks air from the second adsorption cylinder
(35). At that time, the nitrogen components adsorbed on the adsorbent in the second
adsorption cylinder (35) are sucked together with the air by the second pump mechanism
(31b) and desorbed from the adsorbent. As described above, during the first operation,
the air is sucked from the second adsorption cylinder (35) by the second pump mechanism
(31b) and the nitrogen components adsorbed on the adsorbent are desorbed. As a result,
nitrogen-enriched air containing the nitrogen components desorbed from the adsorbent
and having a higher nitrogen concentration and a lower oxygen concentration than the
outdoor air is generated. The nitrogen-enriched air is sucked into the second pump
mechanism (31b), pressurized, and then discharged to the supply passage (44).
«Second operation»
[0106] In the second operation, the control unit (55) switches both the first direction
control valve (32) and the second direction control valve (33) to the second state
illustrated in FIG. 5. The air circuit (3) is thus switched to the second connection
state in which the first adsorption cylinder (34) communicates with the suction port
of the second pump mechanism (31b) but is closed off from the discharge port of the
first pump mechanism (31a), while the second adsorption cylinder (35) communicates
with the discharge port of the first pump mechanism (31a) but is closed off from the
suction port of the second pump mechanism (31b).
[0107] The first pump mechanism (31a) supplies pressurized outdoor air to the second adsorption
cylinder (35). Nitrogen components contained in the air flowing into the second adsorption
cylinder (35) are adsorbed on the adsorbent in the second adsorption cylinder (35).
As described above, during the second operation, the pressurized outdoor air is supplied
from the first pump mechanism (31a) to the second adsorption cylinder (35) and the
nitrogen components in the outdoor air are adsorbed on the adsorbent in the second
adsorption cylinder (35). As a result, oxygen-enriched air having a lower nitrogen
concentration and a higher oxygen concentration than the outdoor air is generated.
The oxygen-enriched air flows from the second adsorption cylinder (35) to the oxygen
discharge passage (45).
[0108] Meanwhile, the second pump mechanism (31b) sucks air from the first adsorption cylinder
(34). At that time, the nitrogen components adsorbed on the adsorbent in the first
adsorption cylinder (34) are sucked together with the air by the second pump mechanism
(31b) and desorbed from the adsorbent. As described above, during the second operation,
the air is sucked from the first adsorption cylinder (34) by the second pump mechanism
(31b) and the nitrogen components adsorbed on the adsorbent are desorbed. As a result,
nitrogen-enriched air containing the nitrogen components desorbed from the adsorbent
and having a higher nitrogen concentration and a lower oxygen concentration than the
outdoor air is generated. The nitrogen-enriched air is sucked into the second pump
mechanism (31b), pressurized, and then discharged to the supply passage (44).
[0109] Note that as described above, during the first operation, the air is pressurized
and the adsorption operation is performed by the first pump mechanism (31a) in the
first adsorption cylinder (34), while the air is decompressed and the desorption operation
is performed by the second pump mechanism (31b) in the second adsorption cylinder
(35). Meanwhile, during the second operation, the air is pressurized and the adsorption
operation is performed by the first pump mechanism (31a) in the second adsorption
cylinder (35), while the air is decompressed and the desorption operation is performed
by the second pump mechanism (31b) in the first adsorption cylinder (34). Therefore,
if the first operation is switched to the second operation or the second operation
is switched to the first operation without the above-described pressure equalizing
operation interposed therebetween, the pressure is extremely low, immediately after
the switching, in the adsorption cylinder in which the desorption operation has been
performed before the switching. Thus, it takes time for the pressure in that adsorption
cylinder to rise, and the adsorption operation is not performed immediately.
[0110] To address this issue, in the present embodiment, when the first operation is switched
to the second operation and when the second operation is switched to the first operation,
the air circuit (3) is switched to the third connection state and the first adsorption
cylinder (34) and the second adsorption cylinder (35) communicate with each other
via the first direction control valve (32) and the second direction control valve
(33). As a result, the internal pressures of the first adsorption cylinder (34) and
the second adsorption cylinder (35) quickly become equal to each other (become a pressure
intermediate between the internal pressures). Such a pressure equalizing operation
quickly raises the pressure in the adsorption cylinder in which the air has been decompressed
and the desorption operation has been performed by the second pump mechanism (31b)
before the switching. As a result, the adsorption operation is performed quickly after
the adsorption cylinder is connected to the first pump mechanism (31a).
[0111] In this way, in the gas supply device (30), the nitrogen-enriched air and the oxygen-enriched
air are generated in the air circuit (3) by the first operation and the second operation
being alternately repeated with the pressure equalizing operation interposed therebetween.
-Effect of embodiment-
[0112] According to the present embodiment, the gas flowing into the filter (76) is heated
by the heating unit (93) in the case where the amount of salt detected by the salt
amount detection unit (91) is equal to or higher than the reference salt amount and
the relative humidity of the gas detected by the humidity detection unit (92) is equal
to or higher than the humidity reference value. Therefore, under the condition where
the humidity is high and deliquescence is likely to occur, moisture is released from
the filter (76), and the occurrence of the deliquescence phenomenon is suppressed.
That is, according to the present embodiment, it is possible to prevent the difficulty
of air passing through the filter (76) during operation.
[0113] According to the above embodiment, the gas flowing into the filter (76) is heated
by the condenser (22) of the refrigerant circuit (20), making it possible to prevent,
with a simple configuration, the difficulty of the gas passing through the filter
(76) during operation.
«Other embodiments»
[0114] The above embodiment may have the following configurations.
[0115] For example, in the above embodiment, the gas supply device (30) sucks air from the
filter unit (75) and supplies nitrogen-enriched air to the interior space (S), i.e.
the target space (S), of the container (11). Alternatively, the target space (S) need
not be the interior space (S) of the container (11), and the gas to be supplied need
not be the nitrogen-enriched air. For example, the gas supply device (30) may supply
gas into a warehouse in a coastal area.
[0116] In the above embodiment, the ACM sensor is used as the salt amount detection unit
(91). Alternatively, the amount of adhering salt may be determined based on the graph
of FIG. 8, or the amount of salt may be determined based on a conversion formula between
the pump operation time and the amount of adhering salt (which is effective when the
ship course is almost the same).
[0117] For example, a sensor provided inside the container (11) may be used as the humidity
detection unit, instead of the humidity sensor provided in the filter atmosphere.
Specifically, for example, when the interior air adjustment device (60) fills the
interior of the container with outdoor air, the air may be introduced into the humidity
sensor in the interior air adjustment device (60) to measure the humidity outside
the container, or a ventilation opening of the container (11) may be opened to take
in the air outside the container, and the humidity may be measured at that time.
[0118] For example, the heating unit (93) may constantly heat the gas flowing into the
filter (76). Even in this case, since the gas flowing into the filter (76) is heated
by the heating unit (93), the occurrence of the deliquescence phenomenon is suppressed.
If the gas flowing into the filter (76) is constantly heated by the heating unit (93),
low-humidity air is supplied to the filter (76). As a result, it is possible to suppress
adherence of moisture to the filter (76), and to suppress the difficulty of gas passing
through the filter (76).
INDUSTRIAL APPLICABILITY
[0119] As described above, the present disclosure is useful for: a gas supply device including
a gas passage through which gas is supplied to a target space, a filter unit provided
at an inlet of the gas passage, and an air pump provided on the gas passage; an interior
air adjustment device that supplies, to the target space, mixed gas having a low oxygen
content and a high nitrogen content; and a container refrigeration device including
the interior air adjustment device.
REFERENCE SIGNS LIST
[0120]
- 10
- Container refrigeration device
- 11
- Container
- 12
- Casing
- 20
- Refrigerant circuit
- 22
- Condenser
- 30
- Gas supply device
- 31
- Air pump
- 38
- Mixed gas generator
- 40
- Gas passage
- 60
- Interior air adjustment device
- 75
- Filter unit
- 76
- Filter (air filter)
- 91
- Salt amount detection unit
- 92
- Humidity detection unit
- 93
- Heating unit